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tetrahedron
Hazard to Others
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what this boils down (or..distils) to is that the methanol found in fermented fruit is of no concern; it's only an issue when deliberately added to
ethanol (either in a legitimate way as a denaturant, or as an illegal additive, much like melamine in chinese milk). of course, here we wanna do
chemistry with our ethanol, not drink it or burn it, so purity matters. it's generally accepted that methanol is impossible to completely remove from
ethanol in an amateur setting. look for 'spirits' that don't use methanol as denaturant.
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AJKOER
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Here is a new idea for the general separation of C2H5OH and CH3OH that may be of academic interest/discussion. I would call it the Chlorate method
which takes advantage of the reducing properties of Methanol to remove/dilute its presence. More specifically, I will first discuss the reaction with
Sulfuric acid that does not work for this separation synthesis. The reaction is reported as:
3 NaClO3 + 2 H2SO4 + .85 CH3OH --> 3 ClO2 + Na3H(SO4)2 + H2O + .o5 CH3OH + .6 CHOOH + .2 CO2
Source: See page 71 at http://books.google.com/books?id=924wS3TfCdIC&pg=PA71&am...
The reaction product is partially confimed at http://www.ahlundberginc.com/chlorine_dioxide_processes.htm . To quote: "Methanol is the reducing agent in the R8 process. The by-product is
sodium sesquisulfate [Na3H(S04)2], an acid salt."
Problem with this synthesis are many including the creation of Formic acid, although this can be removed by employing a slight excess of H2SO4 (with
the accompanying liberation of carbon monoxide). The generated ClO2, also a problem (explosive gas), can, however, be readily dissolved in water:
ClO2 + H2O <--> HClO2 + HClO3
as part of a chlorate regeneration strategy. However, the reason that the synthesis does not work for the separation of Methanol and Ethanol with
Chlorate/Sulfuric acid is that H2SO4 readily (actually exothermic) reacts with the alcohols presence. One possible solution, use HCl which otherwise
requires a ZnCl2 catalyst to react with the alcohols. Upon avoiding an excess of HCl, my speculated reaction (unbalanced) is similar to the sulfuric
reaction with the additional products of Cl2 and perhaps CO:
NaClO3 + HCl + CH3OH --> ClO2 + Cl2 + NaCl + H2O + CH3OH + CHOOH + CO2+ CO
where I continue to assume that the CH3OH acts, given the limited HCl employed, as a reducing agent as well. In addition, it is assumed that a
reaction at room temperature, does not result in a significant loss of the ethanol.
[Edited on 5-11-2012 by AJKOER]
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weiming1998
National Hazard
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Quote: Originally posted by AJKOER  | Here is a new idea for the general separation of C2H5OH and CH3OH that may be of academic interest/discussion. I would call it the Chlorate method
which takes advantage of the reducing properties of Methanol to remove/dilute its presence. More specifically, I will first discuss the reaction with
Sulfuric acid that does not work for this separation synthesis. The reaction is reported as:
3 NaClO3 + 2 H2SO4 + .85 CH3OH --> 3 ClO2 + Na3H(SO4)2 + H2O + .o5 CH3OH + .6 CHOOH + .2 CO2
Source: See page 71 at http://books.google.com/books?id=924wS3TfCdIC&pg=PA71&am...
The reaction product is partially confimed at http://www.ahlundberginc.com/chlorine_dioxide_processes.htm . To quote: "Methanol is the reducing agent in the R8 process. The by-product is
sodium sesquisulfate [Na3H(S04)2], an acid salt."
Problem with this synthesis are many including the creation of Formic acid, although this can be removed by employing a slight excess of H2SO4 (with
the accompanying liberation of carbon monoxide). The generated ClO2, also a problem (explosive gas), can, however, be readily dissolved in water:
ClO2 + H2O <--> HClO2 + HClO3
as part of a chlorate regeneration strategy. However, the reason that the synthesis does not work for the separation of Methanol and Ethanol with
Chlorate/Sulfuric acid is that H2SO4 readily (actually exothermic) reacts with the alcohols presence. One possible solution, use HCl which otherwise
requires a ZnCl2 catalyst to react with the alcohols. Upon avoiding an excess of HCl, my speculated reaction (unbalanced) is similar to the sulfuric
reaction with the additional products of Cl2 and perhaps CO:
NaClO3 + HCl + CH3OH --> ClO2 + Cl2 + NaCl + H2O + CH3OH + CHOOH + CO2+ CO
where I continue to assume that the CH3OH acts, given the limited HCl employed, as a reducing agent as well. In addition, it is assumed that a
reaction at room temperature, does not result in a significant loss of the ethanol.
[Edited on 5-11-2012 by AJKOER] |
Chloric acid is extremely oxidizing, and would oxidise ethanol to acetic acid. I don't think methanol is much more reducing than ethanol, so not all
methanol is going to be destroyed, but a lot of ethanol is going to be destroyed. Chlorine dioxide, a product of the reaction, also oxidizes organics
(a yellow solution of it readily discolours in the presence of ethanol or glycerol, especially when heated).
A second problem is the violence of such a reaction. I have had mini-explosions occur when concentrated sulfuric acid is added to chlorates due to
traces of ethanol in the pipette I used. I expect the whole beaker of alcohol to just catch fire, or even explosively react with the chloric acid.
So overall, I don't think your method will remove methanol to any significant extent and can even be dangerous.
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